This invention relates generally to motion picture cameras having a rotary shutter for interrupting the exposure light beam during the advance of the film. More particularly, this invention relates to cameras having means for selecting the series or the individual picture taking operation with a predetermined or with an optional exposure time.
Reference is had to the applications of Johann Roth et al., Ser. No. 750,306, filed June 26, 1968, now U.S. Pat. No. 3,602,585; Ser. No. 779,051, filed Nov. 26, 1968, now U.S. Pat. No. 3,578,853; and Ser. No. 790,663, filed Jan. 13, 1969 now U.S. Pat. No. 3,603,678.
Known types of motion picture cameras enable the operator to expose a continuous series of pictures, namely a film scene, at a single picture frequency, or with the employment of more picture frequencies. It has also been known how to adapt the motion picture camera to take individual pictures. In either case, a rotary or a to and fro reciprocating shutter, which is driven by the film drive within the camera, covers the exposure light beam during the film advance, thus preventing the film band that is moved about one image past the film gate, from being exposed.
In the series mode of the picture taking operation, the film drive is stopped by the disengagement of the release of the camera and, simultaneously, the rotary shutter takes its closed rest position at which the exposure light beam is covered by the shutter blade.
In the individual picture taking, the shutter is positively locked in its closed rest position after the exposure of a single film image, irrespective of the length of the actuation of the release of the camera. This locked condition of the shutter after the shooting of a single picture is attained generally by mechanical means such as, for example, by a stop that is operatively associated with the release of the camera. At the actuated state of the release, the stop cooperates with a cam on the main transmission shaft of the camera. This main transmission shaft makes one rotation during the advancement phase and the exposure phase of the film.
It has been also suggested to control the stopping of the rotary shutter by electromechanical or electronic means. For example, after the exposure of one picture, an electromagnet has locked the main transmission shaft of the camera either definitely or, for the time-lapse photography, for a predetermined period of time.
In the prior art embodiments, however, there results a uniform exposure time, of about 1/30 sec. maximum, that is predetermined by the motion of the shutter. This exposure time can be shortened by the employment of the so-called adjustable rotary shutter having a continuously variable exposing sector, or by the selection of a higher picture frequency for taking pictures of rapidly moving objects. Such an exposure time in conventional cameras is suitable for the pictures where it is sufficient to determine the contours of moving objects only.
Nevertheless, it is often desirable that the film scenes taken at dawn or in the dark, and containing shots of artificially illuminated objects such as, for example, of the night traffic in streets of a metropolis, or pictures of a people's feast, be combined or interlaced with pictures of eminent buildings, squares or streets at that area. Such a desired combination is usually obstructed due to the insufficient illumination that in most cases makes it impossible to take motion pictures that would reproduce all substantial details, even if powerful light-transmitting lenses are employed.